The present invention relates in general to the continuous vertical bottom casting of a pipe from spheroidal graphite cast-iron, without using a core for forming the cavity of the pipe, and more particularly to an apparatus for supplying molten cast-iron to a tubular die providing the external shape of the pipe, either from a siphon unit (bottom supply), or from a casting ladle under low gas pressure.
The rotary supply of molten casting metal, for example cast-iron, has been known for a long time, for example from French Pat. No. 493,449, with a view to centrifuging the molten metal and obtaining a hollow body and, a little more recently, from U.S. Pat. No. 2,762,096 with a view to homogenizing, i.e. distributing the molten metal uniformly inside the continuous casting mould or ingot-mould. Such rotary supply does not set the bath in rotation, however, owing to the fact that the cast-iron drops vertically without a horizontal component of the speed of rotation.
More recently still, in French Pat. No. 2,352,612, an installation is described for setting the molten cast-iron in rotation at a centrifugation speed using a magnetic field rotating about a crucible containing the molten cast-iron, with a view to obtaining a cast-iron tube by continuous bottom casting, without using a core.
But the problem is posed of setting a mass of molten cast-iron in rotation at a speed lower than the centrifugation speed, for the purpose of homogenizing and regularising the supply, inside a cooled and stationary tubular die, providing the external shape of the tube to be produced, without using a core. The problem is one of maintaining a permanent rotary movement of the molten cast-iron in the stationary and cooled tubular die in order to regularise the thickness of the cast-iron tube obtained on each circular section and thus to obtain internal and external walls which are perfectly concentric.